This book is dedicated to the memory of my wonderful educators and teachers, starting from childhood, studying at school, university and at work. At one time, during their lifetime, we often do not attach importance to their influence on the formation of our worldview, morality and qualifications. And only years later we understand how much they did for us. But they are alive in my memory, and I want to thank them for all the good things they put into us. Thanks to them. Better late than never.